Retaining element to prevent break loose contamination for partially pre-filled syringes

ABSTRACT

Syringe assemblies are provided including a partially pre-filled syringe barrel and a plunger rod that incorporates one or more retention elements on the plunger rod that prevents solution from entering a non-sterile area of the syringe when the plunger rod is pulled back. Methods to manufacture a sterilized partially-filled pre-fill syringe assembly are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application No. 62/868,193, filed Jun. 28, 2019, thedisclosures of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present disclosure relates to syringe assemblies and particularlyto, syringe assemblies having a plunger rod with a retaining elementthat prevents solution from entering a non-sterile area of the syringewhen pulled back for partially pre-filled syringes. The presentdisclosure also relates to methods to manufacture a sterilizedpartially-filled pre-fill syringe assembly.

BACKGROUND

Certain 10 mL syringes which are currently available may include aretaining ring on both the plunger rod and the barrel to prevent thestopper and fluid from moving backward into a non-sterile area. However,the currently available 10 mL syringes having a retaining ring on boththe plunger rod and the barrel are not effective to create apartial-filled syringe having a prefilled volume in the range from morethan 0 mL to less than 10 mL, e.g. 3 or 5 mL, due to the distancebetween the retaining ring on the plunger rod and barrel.

There is also a need for a syringe assembly having a plunger rod withretaining element introduced to prevent solution from entering anon-sterile area of the syringe when the plunger rod is accidentlypulled back for partially pre-filled syringes.

SUMMARY

Syringe assemblies including a plunger rod with a retaining element thatprevents solution from entering a non-sterile area of the syringe whenpulled back for partially pre-filled syringes, and methods tomanufacture the syringe assemblies are described.

One aspect of the present disclosure pertains to a syringe assemblyincluding a barrel, an open proximal end and a distal end, a plunger rodbody disposed within the barrel, and one or more retention elementsdisposed on the plunger rod. The barrel can include a side wall havingan inside surface defining a chamber for retaining a predeterminedamount of pre-filled fluid. The distal end includes a distal wall with atip extending distally therefrom having a passageway therethrough influid communication with said chamber. The plunger rod body is disposedwithin the barrel. The plunger rod can include a distal end including astopper having a distal face and a proximal end. The one or moreretention elements is disposed on the plunger rod at a length from thedistal end of the plunger rod configured to provide increased mechanicalinterference between the plunger rod and barrel when a force is appliedin the proximal direction to prevent the pre-filled fluid from enteringa non-sterile area of the syringe assembly.

In one or more embodiments, the one or more retention elements include aplurality of discontinuities disposed on the outside surface of theplunger rod.

In one or more embodiments, the one or more retention elements extendradially outwardly toward the inside surface of the barrel.

In one or more embodiments, the predetermined amount of pre-filled fluidis in a range from 0 mL to 10 mL, preferably 1 mL, 2 mL, 3 mL, 4 mL, 5mL, 6 mL, 7 mL, 8 mL, 9 ml, and 10 mL. In one or more embodiments, thepredetermined amount of pre-filled fluid is 3 mL. In one or moreembodiments, the predetermined amount of pre-filled fluid is 5 mL.

In one or more embodiments, the one or more retention elements furtherinclude at least one discontinuity disposed on the outside surface ofthe plunger rod, the discontinuity extending radially outwardly towardthe inside surface of the barrel; and at least one retaining ringdisposed on the inside surface of the barrel, the retaining ringextending radially inwardly toward the outside surface of the plungerrod. In one or more embodiments, the at least one discontinuitycooperating with the at least one retaining ring to increase aninterference between the plunger rod and the barrel to require anincreased mechanical force to stop the plunger rod from advancing in aproximal direction.

In one or more embodiments, movement of the plunger rod in a proximaldirection creates an interference between a retaining ring disposed onan inside surface of the barrel and the one or more retention elementsof the plunger.

In one or more embodiments, a portion of the outside surface of theplunger rod is free of retention elements.

In one or more alternate embodiments, the one or more retention elementsinclude a first component having two side walls being level with astraight wall of a crossbar, a sloped top surface having a grade in arange from 1%-100%, one or more flat portions oriented parallel to alongitudinal axis, and a ledge in the sloped top surface that forms aflat end of oriented perpendicular to the longitudinal axis.

In one or more alternate embodiments, the one or more retention elementsfurther include a second component having a tapered wedge that radiallyprotrudes from the straight wall with respect to a medial edge.

In one or more alternate embodiments, the one or more retention elementsfurther include a second component having an oblong protrusion thattapers from the distal end to the proximal end and extends from a curvedwall of the crossbar.

In one or more alternate embodiments, the one or more retention elementsfurther include a second component having a slotted hole in the sidewallof the crossbar positionally aligned behind the retention element alongthe plunger rod.

In one or alternate embodiments, the pre-filled fluid is a solutioncontaining saline, heparin, citrate, pharmaceutical medicament or otherdrugs, or a combination thereof.

In one or more alternate embodiments, the pre-filled fluid is amedicament. In one or more alternate embodiments, the pre-filled fluidis a flush solution.

In one or more embodiments, the syringe assembly is terminallysterilized or with a sterility claim on the fluid path.

Another aspect of the present disclosure pertains to a method ofmanufacture of a sterilized partially-filled pre-fill syringe assembly.A barrel is provided including a side wall having an inside surfacedefining a chamber having a total volume for retaining a predeterminedamount of pre-filled fluid, an open proximal end having a retainingprotrusion and a distal end including a distal wall with a tip extendingdistally therefrom having a passageway therethrough in fluidcommunication with said chamber. A fill volume is preselected, whereinsaid fill volume is substantially less than said total volume. A plungerrod of one or more embodiments described in the present disclosure isprovided. The plunger rod includes one or more retention elements, asdescribed in the present disclosure, disposed on the plunger rod at adistance from the distal end of the plunger rod, said distancecorrelated to said fill volume. The plunger rod is inserted into thebarrel until said retention elements are in a distal position withrespect to the retaining protrusion. The barrel is filled with thepredetermined amount of the pre-filled fluid to said fill volume,wherein said fill volume is substantially less than said total volume.The barrel tip is sealed with a sealing component. In one or moreembodiments, the sealing element is a tip cap. The pre-fill syringeassembly is sterilized. In one or more embodiment, the pre-filledsyringe undergoes a terminal sterilization process via either autoclaveor radiation sterilization in the manufacturing plant to produce sterilepathways of the pre-filled liquid.

In one or more embodiments, the total volume is approximately 3.33 timesthe fill volume. In a specific embodiment, the total volume isapproximately 10 ml and the fill volume is 3 ml.

In one or more alternate embodiment, the total volume is approximately 2times the fill volume. In a specific embodiment, the total volume isapproximately 10 ml and the fill volume is 5 ml.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a transparent top view of the syringe assembly havinga barrel and plunger rod according to one or more embodiments of thepresent disclosure;

FIG. 2 shows a partial transparent top view of the interaction of aplunger rod and barrel of the syringe assembly shown in FIG. 1 ;

FIG. 3 illustrates a side view of a plunger rod according to one or moreembodiments of the present disclosure;

FIG. 4 illustrates a partial bottom-perspective view of the embodimentof the plunger rod shown in FIG. 3 ;

FIG. 5 illustrates a partial bottom-perspective view of an alternativeembodiment of the plunger rod shown in FIG. 3 ;

FIG. 6 illustrates a partial bottom-perspective view of an alternativeembodiment of the plunger rod shown in FIG. 3 ;

FIG. 7 illustrates a partial bottom-perspective view of an alternativeembodiment of the plunger rod shown in FIG. 3 ;

FIG. 8 illustrates a partial top-perspective view of an alternativeembodiment of the plunger rod shown in FIG. 3 ;

FIG. 9 illustrates a partial perspective view of an alternativeembodiment of the plunger rod shown in FIG. 3 ; and

FIG. 10 is a flowchart illustrating a method of manufacturing asterilized partially-filled pre-fill syringe assembly.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the presentdisclosure, it is to be understood that the present disclosure is notlimited to the details of construction or process steps set forth in thefollowing description. The invention is capable of other embodiments andof being practiced or being carried out in various ways.

Syringe assemblies of the present disclosure include a plunger rod withone or more retaining elements that prevents solution from entering anon-sterile area of the syringe when the plunger is accidentally pulledback for partially prefilled syringes. Syringe assemblies of the presentdisclosure include one or more retaining element to prevent break loosecontamination for partially pre-filled syringes.

Syringe assemblies according to a first aspect include a syringe barreland a plunger rod that incorporates a retention element disposed on theplunger rod for interaction with a retaining ring on the syringe barrel.In one or more embodiments, the retaining ring is disposed on an insidesurface of the barrel and extends inwardly into the chamber of thebarrel. The cross-sectional width of the interior surface of the syringebarrel at the retaining ring is less than the cross-sectional width ofthe interior surface at the remaining portions of the syringe barrel. Inone or more embodiments, the retention feature is in the form of amechanical stop. One embodiment of the assembled syringe is shown inFIG. 1 , with alternative embodiments of a plunger rod to be used withthe syringe barrel separately shown in FIGS. 2-9 . Referring to FIGS.1-9 , a syringe assembly according to one embodiment comprises a barrel10 including a side wall 12 having an inside surface 14 defining achamber 16 for retaining fluid, an open proximal end 11 and a distal end19 including a distal wall 17 with a tip 15 extending distallytherefrom. The tip 15 includes a passageway 13 therethrough in fluidcommunication with the chamber 16. As shown in FIG. 1 , the openproximal end 11 includes finger flanges 20. The side wall 12 of thebarrel may be cylindrical or may have another shape.

As shown in FIG. 1 , the tip 15 of the barrel may include a locking luertype collar (as shown in FIG. 1 ) concentrically surrounding tip 15 or aluer slip connection (not shown). In one or more embodiments, the barrelmay include a needless connector. In one or more embodiments, the barrelmay include conventional medical connectors. The collar 18 may includean inside surface having at least one thread thereon. A needle assembly(not shown) including a cannula having a proximal end, a distal end, anda lumen therethrough may also optionally be provided. A hub (not shown)having an open proximal end containing a cavity and a distal end may beattached to the proximal end of the cannula so that the lumen is influid communication with the cavity of the hub. The needle assembly (notshown) is removably attached to the tip of the barrel through engagementof the tip to the cavity of the hub so that the lumen is in fluidcommunication with the chamber of the barrel.

As shown in FIGS. 1 and 3 , a plunger rod 30 is provided and includes aplunger rod body 32 having a proximal end 31, and a distal end 39. Theplunger rod 30 is slidably within the chamber 16 of the barrel 10 fordriving fluid out of the chamber 16. The plunger rod body 32 of theplunger rod extends outwardly from the open proximal end 11 of thebarrel and may be disposed within the chamber 16. The plunger rod 30includes a thumb press 29 at the proximal end 31 and a stopper 40 at thedistal end 39. The stopper 40 includes a sealing edge 42 that forms aseal with the inside surface 14 of the barrel. The shape of the plungerrod may be modified to fit within barrels with side walls havingdifferent shapes.

The plunger rod body 32 of the plunger rod includes an outside surface34, forming a perimeter around the plunger rod body 32 and an axiallength extending from the proximal end 31 to the distal end 39. Theplunger rod body 32 may include a single beam or structure, which mayhave cylindrical or other shapes. As shown in FIGS. 1-9 , the bodyportion 32 may be formed by two perpendicularly intersecting beams 37.The beams may have a rectangular cross-section. In the embodiment shown,the two intersecting beams 37 intersect to form an outside surfaceoutlining four quadrants 51, 52, 53, 54 (shown more clearly in FIG. 3 )that face the inside surface 14 of the barrel and extend along the axiallength from the proximal end 31 to the distal end 39 of the plunger rod.

In a preferred embodiment, as illustrated in FIG. 3 , the plunger rodbody includes two intersecting beams 37 that intersect to form aperpendicular crossbar 44 having an outside surface outlining fourquadrants of a cruciform. For purposes of illustration, three quadrants51, 52, 53 of the four quadrants are shown. The perpendicular crossbars44 are longitudinally integrated with the thumb press 29 and thestopper-engaging portion 28. The body of the rod plunger is not limitedto being cruciform, nor do the crossbars 44 necessarily need to beperpendicular or symmetrical. The body of the rod plunger 32 maycomprise of another geometric shape that can be inscribed within thechamber 16 of the syringe barrel 10. For instance, the body of the rodplunger may be triangular or rectangular.

A stopper-engaging portion 28 having a threaded region is disposedadjacent to the distal end 39 for fastening of a stopper. In one or moreembodiments, the threaded region of the stopper-engaging portion 28 isconfigured to receive corresponding threads of a stopper. In a specificembodiment, the plunger rod and stopper may be integrally formed orpermanently attached. In accordance with one or more embodiments of thepresent disclosure, the stopper-engaging portion 28 is shaped to fitwithin the stopper cavity of the stopper and to retain the stopper atthe distal end of the plunger rod.

Adjacent to the threaded region is the plunger rod body. The plunger rodbody is disposed within the chamber 16 and moveable in the proximal anddistal direction within the chamber 16, respective to the syringe barrel10.

The plunger rod body and the retaining element may be made of a rigidplastic or other material. Examples of such materials includepolypropylene, polyethylene, polycarbonate and combinations thereof.

The stopper 40 of one or more embodiments may be integrally formed onthe distal end 39 of the plunger rod or may form a separate componentthat is connected to the distal end 39 of the plunger rod. The distalend 39 of the plunger rod may include an integrally formed stopper. Asshown in FIG. 1 , the stopper 40 may include a conically-shaped distalsurface and the barrel may include a conically-shaped inside surface atits distal wall. The stopper 40 is slidably positioned in fluid-tightengagement with the inside surface 14 of the barrel for drawing fluidinto and driving fluid out of the chamber.

The stopper 40 may be made of any material suitable for providing a sealwith the inside surface 14 of the barrel. For example, the stopper 40may be made of thermoplastic elastomers, natural rubber, syntheticrubber or thermoplastic materials and combinations thereof. The stopper40 may be integrally formed or composed of separate components of thesame or different materials joined together. The plunger rod 30 may bemade of material which is more rigid than the stopper such aspolypropylene, polyethylene and the like. Materials should be chosen tobe compatible with the procedure being used.

In the embodiments shown in FIGS. 1-9 , one or more retention elements36 are disposed on the outside surface of the body portion 32 of theplunger rod. More specifically, the one or more retention elements aredisposed on the outside surface of the four quadrants (51, 52, 53). Theretention elements 36 may be integrally formed or provided as separatecomponents that may be added to the plunger rod. In one or moreembodiments where retention elements 36 are provided as separatecomponents, the plunger rod 30 or barrel 10 may further include astructure for the attachment of separate retention elements 36. In oneor more embodiments, the chamber of the barrel may accommodate 10 mL offluid. In one or more embodiments, the pre-filled fluid is a solutioncontaining saline, heparin or citrate or other drugs or medicament. Inone or more embodiments, the pre-filled fluid is a flush solution or amedicament. A 10 mL chamber 16 of the barrel may be prefilled with apredetermined amount of solution in a range from 0 mL to 10 mL,preferably 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, 8 mL, 9 ml, and 10mL, wherein the retention element disposed on the plunger rod of thepresent disclosure interacts with the retaining ring on the insidesurface of the barrel to prevent the pre-filled solution from entering anon-sterile area of the syringe if the plunger rod is accidently pulledback by the end user. In one or more embodiments, the chamber 16 of thebarrel is prefilled with 3 mL of solution. In one or more alternateembodiment, the chamber 16 of the barrel is prefilled with 5 mL ofsolution. In one or more embodiments, the retaining ring is disposed onthe inside surface of the barrel at the proximal end of the barrel. Inone or more embodiments, the retaining ring is disposed on the insidesurface of the barrel to interact with the retention element of theplunger rod to allow a predetermined amount of fluid in a range from 0mL to 10 mL, such as 3 or 5 mL, which was pre-filled in the chamber ofthe barrel and to prevent the pre-filled solution from entering anon-sterile area of the syringe if the plunger rod is accidently pulledback by the end user.

As shown in FIG. 1 , one embodiment of the present disclosure relates toa syringe assembly 6 having a barrel whose chamber can be pre-filledwith a predetermined amount of fluid in a range from 0 mL to 10 mL, suchas 3 or 5 mL, and having retaining element 36 disposed at a fixedposition along the length of a plunger rod body 32 to prevent thepre-filled solution from leaving a sterile area “A” and entering anon-sterile area “B” located beyond the retaining element 36 if theplunger rod is accidently pulled back by the end user into a non-sterilearea.

In one or more embodiments, the plunger rod 30 includes an integralretaining element 36 along the length of a plunger rod body 32 tocontrol the maximum relative position the plunger rod 30 can distallyextend from the distal end 19 of the syringe assembly. When theretaining element 36 abuts against a retaining ring within the chamber16 of the syringe barrel 10, the retaining element 36 of the plunger rodprevents the plunger rod from further extending from the distal end 19of the syringe 6 beyond a desired point to prevent the pre-filledsolution from entering a non-sterile area of the syringe when theplunger rod is accidently pulled back for partially pre-filled syringes.The position of the retaining element 36 on the plunger rod body 32 isdetermined by the amount of fluid volume that is prefilled into thesyringe barrel 10 such that the retaining element 36 preventing thepre-filled solution from entering a non-sterile area of the syringe ifthe plunger rod is accidently pulled back by the end user.

In the present disclosure, a convention is followed wherein the medialdirection is the direction pointing perpendicularly towards thelongitudinal axis 5, and the lateral direction is the direction pointingperpendicularly away from the longitudinal axis 5.

As shown in FIG. 2 , the syringe barrel 10 comprises of a chamber 16. Inone or more embodiments, the maximum volume of the chamber is 10 mL. Inone or more embodiments of the present disclosure, the volume ofprefilled fluid in chamber 16 can be in the range of 0 mL to 10 mL,preferably 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, 8 mL, 9 ml, and 10mL. Within the chamber 16 exists a retaining ring or retaining ring 21closely adjacent proximal end 11 of the syringe barrel 10. Retainingring 21 extends medially into the chamber 16 of the syringe barrel 10.The retaining ring 21 prevents the retaining element 36 from proximaltranslation once the retaining element 36 is approaching or abutted tothe retaining ring 21 to prevent the pre-filled solution from entering anon-sterile area of the syringe when the plunger rod is accidentlypulled back.

As shown in FIGS. 2 and 3 , an alternate embodiment of the plunger rod30 comprises one or more retention elements 36 disposed along the lengthof the crossbars 44 such that when the plunger rod is disposed into a 10mL syringe barrel, the plunger rod will limit the pre-filled volume inthe syringe chamber 16 in a range from 0 mL to 10 mL, e.g. 3 mL or 5 mL,and prevent the pre-filled solution from entering a non-sterile area ofthe syringe if the plunger rod is accidently pulled back by the enduser. More specifically, the one or more retention elements are disposedon the outside surface of the four quadrants (51, 52, 53). The retainingelement is disposed along the plunger rod body at the farthest medialend of the crossbars 44. The one or more retaining element is disposedalong the plunger rod body at a length of a plunger rod body 32 to allowa user to administer a desired amount of flush solution or medicament ina range from 0 mL to 10 mL, e.g. 3 mL or 5 mL, depending on the locationthat the retaining element is disposed along the plunger rod. In one ormore embodiments, the retaining element of the plunger rod interactswith a retaining ring or retaining ring 21 disposed on the insidesurface of the chamber 16 of the syringe barrel 10 and extendingradially inwardly toward the chamber and/or a plunger rod. The retainingring 21 interacts with the retention elements 36 disposed on the plungerrod 30 to prevent the pre-filled solution from entering a non-sterilearea of the syringe if the plunger rod is accidently pulled back by theend user. In such embodiments, the retaining ring 21 forms a narrowedcross-sectional width in comparison to the cross-sectional width formedby the inside surface 14 of the barrel. The inside surface 14 of thebarrel has a smaller cross-sectional width at the retaining ring 21.

For one or more specific embodiment, as shown in FIG. 4 , the mechanicalstop of the plunger rod is disposed on crossbars 44 and include morethan one straight walls 41 and a curved wall 43.

As shown in FIG. 4 , the retaining element 100 is in the shape of a“shark fin”. The retaining element 100 is a discontinuity along thelength of the plunger rod body 32 on the curved wall 43. The retainingelement 100 comprises of a sloped surface 102. The sloped surface 102 isoutwardly tapered towards the proximal end 31 of the plunger rod body32. The side walls 104 of the retaining element 100 are level with thestraight wall 41 of the crossbar 44. The retaining element 100 may alsohave one or more flat portions 106 that run parallel to the longitudinalaxis 5. There is a drop-off or ledge in the sloped surface that forms aflat end 108 of retaining element 100. The flat end 108 is perpendicularto the longitudinal axis 5.

In one or more embodiments, the retaining element 100 in the form of the“shark fin” protrudes radially from the outside surface of the fourquadrants (51, 52, 53). In one or more embodiments, the retainingelement 100 in the form of the “shark fin” has a thickness equal to orslightly less than a thickness of the four quadrants (51, 52, 53). Inone or more embodiments, the retaining element 100 in the form of the“shark fin” does not project tangentially from the four quadrants (51,52, 53).

As shown in FIGS. 5 and 6 , an alternate embodiment of the plunger rodincludes a retaining element 200 having two components disposed andintegrated into wall 43 of alternating crossbars 44. The retainingelement 200 is a discontinuity along the length of the plunger rod body32 disposed on the curved wall 43. The first component 210 of theretaining element is in the shape of a “shark fin” and is integratedinto the curved wall 43 of the crossbar 44 and comprises a slopedsurface 202. The sloped surface 202 outwardly tapers towards theproximal end 31 of the plunger rod body 32. The side walls 204 of theretaining element 200 are level with the straight wall 41 of thecrossbar 44. The retaining element 200 may also have one or more flatportions 206 that run parallel to the longitudinal axis 5. There is adrop-off or ledge in the sloped surface that forms a flat end 208 ofretaining element 200. The flat end 108 is perpendicular to thelongitudinal axis 5.

The second component 220 of the retaining element 200 is a discontinuityintegrated into the curved wall 43 of alternating crossbars 44, whereintwo of the crossbars 44 have the first component 210 in the form of the“shark fin” and alternating two of the crossbars have the secondcomponent 220. The second component 220 is in the shape of a taperedwedge and is integrated into the curved wall 43 of the crossbar 44. Thesecond component 220 comprises of a sloped surface 222 that outwardlytapers towards the proximal end 31 of the plunger rod body 32. Theretaining element 200 may also have one or more flat portions 226 thatrun parallel to the longitudinal axis 5. The side walls 224 of thesecond component 220 protrude outward from the mid-plane and extendmedially onto the straight wall 41 of the crossbar 44 to “envelope” thecrossbar 44 of the plunger rod body 32. Alike the sloped surface 222,the side walls 224 of the second component 220 outwardly tapers towardsthe proximal end 31 of the plunger rod body 32. There is a drop-off fromthe sloped surface 222 and the side walls 224 that form the flat end 228of the second component 220 of the retaining element 200.

Within the body of the rod plunger, there may be only a singleembodiment or a combination of embodiments of the retaining elements 100and 200 used throughout the plunger rod body 32.

As shown in FIG. 7 , an alternate embodiment of the plunger rod includesa retaining element 300 having two components disposed and integratedinto alternating crossbars. The retaining element 300 is a discontinuityalong the length of the plunger rod body 32 on the curved wall 43. Thefirst component 310 of the retaining element is in the shape of a “sharkfin” and is integrated into the curved wall 43 of the crossbar 44 andcomprises a sloped surface 302. The sloped surface 302 outwardly taperstowards the proximal end 31 of the plunger rod body 32. The side walls304 of the first component 310 are level with the straight wall 41 ofthe crossbar 44. The first component 310 may also have one or more flatportions 306 that run parallel to the longitudinal axis 5. There is adrop-off or ledge in the sloped surface that forms a flat end 308 of thefirst component 310. The flat end 108 is perpendicular to thelongitudinal axis 5.

The second component 320 of the retaining element is in the shape of a“shark tail” and is integrated into the curved wall 43 of alternatingcrossbars 44. The second component 320 comprises of a sloped surface322. The sloped surface 322 outwardly tapers towards the proximal end 31of the plunger rod body 32. The side wall 329 of the second component320 protrudes outwards from the crossbar 44 and outwardly tapers towardsthe proximal end 31 of the plunger rod body 32, aligned with the slopedsurface 322. The retaining element 300 may also have one or more flatportions 306 that run parallel to the longitudinal axis 5. There is adrop-off in the sloped surface 322 and the side wall 329 that forms aflat end 328 of the second component 320. The flat end 328 isperpendicular to the longitudinal axis 5.

As shown in FIG. 8 , an alternate embodiment of the plunger rod includesa retaining element 400 having two components disposed and integratedinto alternating crossbars. The retaining element 400 is a discontinuityalong the length of the plunger rod body 32 on the curved wall 43. Thefirst component 410 of the retaining element is in the shape of a “teardrop” and is integrated into the curved wall 43 of the crossbar 44 andcomprises a sloped surface 402. The sloped surface 402 outwardly taperstowards the distal end 39 of the plunger rod body 32. The oppositetapering design provides a resistive force to the sloped surface 402 asit frictionally engages with the retaining ring 21 and prevents thepre-filled solution from entering a non-sterile area of the syringe whenthe plunger rod is pulled back. This results in a stoppage of theproximal translation of the plunger rod 30 relative to the syringebarrel 10. The side walls 404 of the retaining element 400 are levelwith the straight wall 41 of the crossbar 44.

In one or more embodiments, the first component 410 protrudes radiallyfrom the outside surface of the four quadrants (51, 52, 53). In one ormore embodiments, the first element 410 has a thickness equal to orslightly less than a thickness of the four quadrants (51, 52, 53). Inone or more embodiments, the first element 410 in the form does notproject tangentially from the four quadrants (51, 52, 53).

The second component 420 of the retaining element 400 is in the shape ofa “submarine” and is integrated into the curved wall 43 of alternatingcrossbars 44 and comprises a sloped surface 422. The sloped surface 422of the second component 420 outwardly tapers towards the distal end 39of the plunger rod body. The sloped surface 402 outwardly tapers towardsthe distal end 39 of the plunger rod body 32. The sloped surface 422 ofthe second component 420 outwardly tapers providing a resistive force tothe sloped surface 422 as it frictionally engages with the retainingring 21 when the plunger rod is accidently pulled back by an end user.This causes a stoppage of the proximal translation of the plunger rod 30relative to the syringe barrel 10. The second component 420 alsocomprises of a side wall 428 that medially extends into the crossbar 44.In one or more embodiments the second component 220 protrudestangentially with respect to the curved wall 43. In one or moreembodiments, the second component 220 also contacts and envelopes aportion of the crossbars 44 of which they are situated upon.

In one or more embodiments, the first component 410 of the retainingelement and the second component 420 of the retaining element aredisposed on alternating crossbars 44, wherein two of the crossbars 44have first component 410 and alternating two of the crossbars have thesecond component 420.

In one or more embodiments, the plunger rod 30 may comprise of acombination of the retaining element with or without walls that arelevel to the straight wall of the crossbar.

One or more embodiments of the plunger rod having retaining element 400provides the end user with a prolonged period of time to stop the pullback motion as the resistance force builds up.

An alternate embodiment of the plunger rod is shown in FIG. 9 . As shownin FIG. 9 , the retaining element 500 is in the shape of a “shark fin”.The retaining element 500 is a discontinuity along the length of the rodplunger body 32 on the curved wall 43. The retaining element 500comprises of a sloped surface 502. The sloped surface 502 outwardlytapers towards the proximal end 31 of the plunger rod body 32. The sidewalls 504 of the retaining element 500 are level with the straight wall41 of the crossbar 44. The retaining element 500 may also have one ormore flat portions 506 that run parallel to the longitudinal axis 5.There is a drop-off or ledge in the sloped surface that forms a flat end108 of retaining element 100. The flat end 508 is perpendicular to thelongitudinal axis 5. In one or more embodiments, the retaining element500 further comprises a plurality of tangential ribs 503 disposed uponthe sloped surface 502

Medial to the retaining element 500 on the plurality of crossbars 44exists a slotted hole 60 along the plunger rod 30 as shown in FIG. 9 .The slotted holes allow the retaining element 500 to deflect in a medialand lateral direction. The slotted hole 60 allows flexure of theretaining element 500 and the surface it is integrated on. This addedflexibility allows for the plunger rod 30 to be assembled within thesyringe barrel 10. To assemble the medical syringe 6, the distal end ofthe plunger rod 30 is inserted into the proximal end 11 of the syringebarrel 10. As the plunger rod enters the syringe barrel, the retainingring 21 within the chamber 16 of the syringe barrel 10 exerts a force onthe sloped surface 502 of the retaining element 500. The slotted hole 60on the straight wall 41 of the crossbars 44 allow for the retainingelement 500 to deflect in the medial direction. Once the flat end 508 onthe retaining element 500 clears the retaining ring 21 in the syringebarrel 10, the retaining element 500 snaps back from its deflectedposition and produces an audible “click” upon completion of the assemblyof the medical syringe 6.

In one or more embodiments, a plunger rod having a combination of any ofthe retaining elements described herein may also include the slottedhole 60 in the plurality of crossbars 44.

As shown in FIGS. 1-9 , a plurality of retaining element may be disposedalong the axial length of the plunger rod and may be disposed atpre-defined intervals along the axial length. In a specific embodiment,the pre-defined intervals are equally spaced. The plurality of retainingelements may be disposed along the axial length of the plunger roddetermined by the amount of pre-filled solution in a range from 0 mL to10 mL, such as 3 mL or 5 mL, such that the stopper is prevented frombeing pulled back to the point where the pre-filled solution can enterthe non-sterile area behind the original location of the back of thestopper rib.

In one or more embodiments, one or more retaining element 36 may beperipherally formed along a segment of the outside surface of theplunger rod, while the remaining segments of the outside surface arefree of any retaining element.

The one or more retaining element 36 of plunger rod body 32 interactwith the retaining ring 21 of the syringe barrel when a force is appliedto the plunger rod in the proximal direction caused by accidental pullback by the end user.

In operation, the syringe assemblies when used with the plunger rodsdescribed herein are pre-filled with flush solution or medicament usingknown methods. The pre-filled syringe undergoes a terminal sterilizationprocess via either autoclave or radiation sterilization in themanufacturing plant to produce sterile pathways of the pre-filledliquid. In one or more embodiments, the flush solution may be anysolution intended for flushing or maintaining the performance ofvascular access devices (VADs). Exemplary flush solutions include salineflush solution and/or heparin lock flush solution. These solutions areknown in the art and readily available. An example of a saline flushsolution is 0.9% Sodium Chloride USP for injection. An example of aheparin lock flush solution is 0.9% Sodium Chloride with 100 USP unitsof Heparin Sodium per ml or 10 USP units of Heparin Sodium per ml. Onceassembled, the syringe assembly may be used by the end user toadminister a pre-filled medicament or flushing a VAD such as a catheterof an I.V. set by providing a distal force. In order to protect fromaccidental pull-back, the retaining features described in the presentdisclosure prevent the stopper being pulled back to the point where thesolution can enter the non-sterile area behind the original location ofthe back of the stopper rib.

In accordance with one or more embodiments, the one or more retainingelement 36 disposed on the plunger rod are shaped to interfere or formenhanced mechanical interference with the syringe barrel during movementof the plunger rod in the proximal direction. Changes in mechanicalforces between the plunger rod and barrel impede, slow or stop movementof the plunger rod in the event that the user applies an accidentalforce to the plunger rod in the proximal direction.

Another aspect of the present disclosure pertains to a method ofmanufacturing a sterilized partially-filled pre-fill syringe assembly.An exemplary method of manufacture 600 is shown in FIG. 10 . Thereference numerals used to describe the various elements below coincidethe elements shown in FIGS. 1-9 . As shown in step 610 of FIG. 10 , abarrel 10, as shown in FIG. 1 , is provided including a side wall 12having an inside surface 14 defining a chamber 16 having a total volumefor retaining a predetermined amount of pre-filled fluid, an openproximal end 11 having a retaining protrusion and a distal end 19including a distal wall 17 with a tip extending distally therefromhaving a passageway therethrough in fluid communication with saidchamber. As shown in step 620 of FIG. 10 , a fill volume is preselected,wherein said fill volume is substantially less than said total volume.As shown in step 630 of FIG. 10 , a plunger rod 30 of one or moreembodiments described in the present disclosure and as shown in FIGS.1-9 is provided. The plunger rod 30 includes a distal end, a stopper anda proximal end. The plunger rod includes one or more retention elements,as described in the present disclosure, disposed on the plunger rod at adistance from the distal end of the plunger rod, said distancecorrelated to said fill volume. The one or more retention elements 36are configured to provide increased mechanical interference between theplunger rod 30 and barrel 10 retaining protrusion. As shown in step 640of FIG. 10 , the plunger rod is inserted into the barrel 10 until saidretention elements are in a distal position with respect to theretaining protrusion. As shown in step 650 of FIG. 10 , the barrel 10 isfilled with the predetermined amount of the pre-filled fluid to saidfill volume, wherein said fill volume is substantially less than saidtotal volume. As shown in step 660 of FIG. 10 , the barrel tip is sealedwith a sealing component. In one or more embodiments, the sealingelement is a tip cap. As shown in step 670 of FIG. 10 , the pre-fillsyringe assembly is sterilized. In one or more embodiment, thepre-filled syringe undergoes a terminal sterilization process via eitherautoclave or radiation sterilization in the manufacturing plant toproduce sterile pathways of the pre-filled liquid. In one or moreembodiments, the step of sterilizing said pre-fill syringe assemblyoccurs before inserting the plunger rod into the barrel until saidretention elements are in a distal position with respect to saidretaining protrusion.

In one or more embodiments, the total volume is approximately 3.33 timesthe fill volume. In a specific embodiment, the total volume isapproximately 10 ml and the fill volume is 3 ml.

In one or more alternate embodiment, the total volume is approximately 2times the fill volume. In a specific embodiment, the total volume isapproximately 10 ml and the fill volume is 5 ml.

In one or more embodiments, the one or more retention elements includesa first component having two side walls being level with a straight wallof a crossbar, a sloped top surface having a grade in a range from1%-100%, one or more flat portions oriented parallel to a longitudinalaxis, and a ledge in the sloped top surface that forms a flat end oforiented perpendicular to the longitudinal axis, as shown in FIGS. 3 and4 .

In one or more alternate embodiment, the one or more retention elementsfurther includes a second component having a tapered wedge that radiallyprotrudes from the straight wall with respect to a medial edge, as shownin FIG. 5-7 .

In yet another alternate embodiment, the one or more retention elementsfurther includes a second component having an oblong protrusion thattapers from the distal end to the proximal end and extends from a curvedwall of the crossbar, as shown in FIG. 8 .

In yet another alternate embodiment, the one or more retention elementsfurther includes a second component having a slotted hole in thesidewall of the crossbar positionally aligned behind the retentionelement along the plunger rod, as shown in FIG. 9 .

In one or more alternate embodiment, the retaining protrusion is a disk,gasket or O-ring.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular element, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular elements, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A syringe assembly comprising: a barrel includinga side wall having an inside surface defining a chamber for retaining apredetermined amount of pre-filled fluid, an open proximal end and adistal end including a distal wall with a tip extending distallytherefrom having a passageway therethrough in fluid communication withsaid chamber; a plunger rod disposed within the barrel, the plunger rodcomprising a distal end, a proximal end and an outside surface, whereinthe distal end of the plunger rod including a stopper having a distalface, a plunger rod body extending from the proximal end of the plungerrod to the distal end of the plunger rod; and one or more retentionelements disposed on the plunger rod at a length from the distal end ofthe plunger rod configured to provide increased mechanical interferencebetween the plunger rod and barrel when a force is applied in a proximaldirection to prevent the pre-filled fluid from entering a non-sterilearea of the syringe assembly, wherein the one or more retention elementscomprise a first component having two side walls being level with astraight wall of a crossbar, a sloped top surface having a grade in arange from 1%-100%, one or more flat portions oriented parallel to alongitudinal axis, and a ledge in the sloped top surface that forms aflat end of oriented perpendicular to the longitudinal axis.
 2. Thesyringe assembly of claim 1, wherein the one or more retention elementscomprises a plurality of discontinuities disposed on the outside surfaceof the plunger rod.
 3. The syringe assembly of claim 2, wherein the oneor more retention elements extend radially outwardly toward the insidesurface of the barrel.
 4. The syringe assembly of claim 1, wherein thepredetermined amount of pre-filled fluid is in a range from 0 mL to 10mL.
 5. The syringe assembly of claim 4, wherein the predetermined amountof pre-filled fluid is 3 mL.
 6. The syringe assembly of claim 4, whereinthe predetermined amount of pre-filled fluid is 5 mL.
 7. The syringeassembly of claim 1, wherein the one or more retention elementscomprise: at least one discontinuity disposed on the outside surface ofthe plunger rod, the discontinuity extending radially outwardly towardthe inside surface of the barrel; and at least one retaining ringdisposed on the inside surface of the barrel, the retaining ringextending radially inwardly toward the outside surface of the plungerrod, the at least one discontinuity cooperating with the at least oneretaining ring to increase an interference between the plunger rod andthe barrel to require an increased mechanical force to stop the plungerrod from advancing in a proximal direction.
 8. The syringe assembly ofclaim 7, wherein movement of the plunger rod in a proximal directioncreates an interference between a retaining ring disposed on an insidesurface of the barrel and the one or more retention elements of theplunger.
 9. The syringe assembly of claim 1, wherein a portion of theoutside surface of the plunger rod is free of retention elements. 10.The syringe assembly of claim 1, wherein the one or more retentionelements further comprise a second component having a tapered wedge thatradially protrudes from the straight wall with respect to a medial edge.11. The syringe assembly of claim 1, wherein the one or more retentionelements further comprises a second component having an oblongprotrusion that tapers from the distal end to the proximal end andextends from a curved wall of the crossbar.
 12. The syringe assembly ofclaim 1, wherein the one or more retention elements further comprises asecond component having a slotted hole in a sidewall of the crossbarpositionally aligned behind the retention element along the plunger rod.13. The syringe assembly of claim 1, wherein the pre-filled fluid is asolution containing saline, heparin or citrate or other drugs.
 14. Thesyringe assembly of claim 1, wherein the fluid is a pre-filledmedicament.
 15. The syringe assembly of claim 1, wherein the syringeassembly is terminally sterilized.
 16. A method of manufacturing asterilized partially-filled pre-fill syringe assembly comprising:providing a syringe assembly of claim 1; preselecting a fill volume,wherein said fill volume is substantially less than said total volume;inserting the plunger rod into the barrel until said retention elementsare in a distal position with respect to a retaining protrusion; fillingsaid barrel with a predetermined amount of said pre-filled fluid to saidfill volume, wherein said fill volume is substantially less than a totalvolume; sealing a barrel tip with a sealing component; and sterilizingsaid pre-fill syringe assembly.
 17. The method of claim 16, wherein thetotal volume is approximately 3.33 times the fill volume.
 18. The methodof claim 17, wherein the total volume is approximately 10 ml and thefill volume is 3 ml.
 19. The method of claim 16, wherein the totalvolume is approximately 2 times the fill volume.
 20. The method of claim19, wherein the total volume is approximately 10 ml and the fill volumeis 5 ml.
 21. The method of claim 16, wherein the retaining protrusion isa disk, gasket or O-ring.
 22. The method of claim 16, wherein thesterilizing said pre-fill syringe assembly occurs before inserting theplunger rod into the barrel until said retention elements are in adistal position with respect to said retaining protrusion.